10 things we learned driving the 2015 Dodge Challenger SRT Hellcat

Subtlety is not its strong point.

Big numbers and small numbers. Up to this point, what you know about the Hellcat-packing Challenger is that its big numbers—707 hp and 650 lb-ft of torque—produce some small ones: Dodge says it'll do the quarter-mile in 11.2 seconds at 125 mph with the stock Pirellis. On drag radials, the time drops to 10.8 at 126.

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And now we've driven it, including some time spent attempting small numbers of our own. So here are 10 things you need to know about the quickest, most powerful stock muscle car ever produced.

1. Few engines are as appropriately named.

At full throttle, the Hellcat sounds so damned pissed-off that you might think there's another behind you, one on either side, and maybe one above and below, too. This imaginary formation makes perfect sense, as the name is military-derived; Hellcat fighter aircraft and tank destroyers (which were, um, built by Buick) fought on our side in WWII. Dodge's history of militarized engine monikers—Tigershark, Apache, Viper—is strong, but this one, and the noise the engine makes, wins.

A 2.75-inch exhaust system uses resonators front and rear, with electronically controlled valves that can bypass the ones out back. The amount of flow is dictated by the drive modes—in track mode, it's gloriously loud, but in the default setup at a highway cruise it avoids annoying drone. It's a high-tech approach compared to the block-off plates on a Boss 302 Mustang, or even the vacuum-operated valves in Corvettes and Camaros, providing more control and customization, but I'm pretty sure people will find the fuse and pull it. I will the next time I'm in one. Hellfury!

Chrysler

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2. A lot had to change to make the first factory-supercharged Hemi.

By part value, the Hellcat engine is 91 percent new compared to the 6.4-liter Apache V8 on which it's based. New stuff: rocker covers, high-heat heads, high-heat exhaust valves, pistons, connecting rods, crankshaft, block, oil pan, oil pump. And, of course, the supercharger. Most of the carryover was measurements (bore, bore centers, valve locations), fasteners, and hang-on parts like the alternator.

3. It's the fifth-most-powerful production car today.

What's ahead of it? The LaFerrari, McLaren P1, Porsche 918 Spyder, and Ferrari F12. Note that three of the top five are Fiat-Chryslers. Sergio likes him some power. Chrysler had to upgrade its dyno cells just to test the engine.

4. Heat is the enemy of efficiently making an ungodly hellstorm of power.

Not a lot of new ideas went into making 222 more horsepower than the naturally aspirated 6.4-liter. The main concern was keeping everything cool enough to reach those numbers. That means a separate low-temp cooling loop for the intercoolers (a setup originally cooked up for use in high-efficiency small-displacement applications), cooling for the transmission, and a big oil cooler. To feed it, they popped a hole in the left parking lamp to ram-air the airbox. One of the development targets was for the car to endure a 20-minute track session in 100-plus-degree heat without having to start pulling power from the engine.

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Chrysler

5. The Hellcat needs a bigger automatic transmission.

As in physically larger. All 2015 Challenger autos are eight-speeds, but the one in the Hellcat uses stronger, wider gears, which makes the transmission case longer. It shifts quickly at full-throttle, too, with a little kick to let you know it's after speed and not smoothness in track mode. The Hellcat's standard Tremec six-speed manual was borrowed from the Viper but adds an external oil cooler. It shifts as smoothly and as quickly as you desire.

6. The engine was just part of the upgrade, albeit a big part.

The Hellcat weighs about 210 pounds more than the SRT 392 but, well, it doesn't feel like it. To deal with added weight but also to fix some of the previous model's boat-like tendencies, the Hellcat gets much larger sway bars. You notice them immediately on a road course. Instead of seeming like it's going to tip, the body stays flat enough to inspire a little confidence, letting the 9.5-inch-wide Pirellis out back do their job. And to make sure the thing actually stops, the front brakes have been upgraded from four-piston to six-piston calipers, clamping onto discs with lightweight aluminum hats. A testament to the brake system: I was a lot more concerned with bad things happening when I went for the right pedal than when I went to scrub the speed it wrought.

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7. Patience is a virtue, street or strip.

Yes, you can steer the Hellcat Challenger with your right foot. This much should not surprise you. What came as a bit of a shock was how easily this can be done. Comfortably long throttle travel makes it a progressive walk from idling in traffic to roasting the black 20-inch marshmallows. The chassis is surprisingly neutral, which gives you leeway, which you might need, because: 650 freaking lb-ft of torque.

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But don't think it's tough to get roasting. A pre-drag burnout is a side-step away. Even with minimal brake-torquing (we revved to 1500 rpm before dropping the hammer on a Hellcat auto) it'll put an angle between the car and the wall very quickly. Recovery from such a stylish leave from the line is again aided by that long right pedal. Then you just line up again and tell everyone you weren't going for a time.

8. Doesn't look that different, doesn't really need to.

A Challenger is instantly recognizable. The changes for the 2015 model evolve the styling from '70-aping to '71-inspired. It all works, even if the car looks like a 6:5 scale model of the original. But unlike the big-power Camaros and Mustangs, the muscliest Challenger doesn't have a ton of styling differentiation compared to a base V6 car. Changes are subtle: SRT in the grille, an aluminum hood with heat extractors flanking a scoop, a lowered grille brow, a deeper splitter, and a taller spoiler. Aside from the "SUPERCHARGED" badges, there's very little ornamentation to suggest nutso power. The thinking seems to be: Once it starts moving, you'll know.

Chrysler

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9. Two keys, because you shouldn't trust yourself.

Red fob gives access to every last one of the 707 hp. Black fob limits output to 500 hp, or slightly more than a stock SRT 392. Call it rain mode. Since few can be trusted with absolute power, valet mode limits the engine to 4000 rpm, keeps ESC on all the time, and, on automatic models, alters shift points and starts out in second.

10. You can't put a Hellcat engine in a Viper. You shouldn't want to.

For those wondering what Chrysler's most-powerful-ever engine is doing in anything but the Viper: two different animals. The SRT people describe the Viper as a track car you can drive on the street and the Hellcat as a street car that can go to the track. The Hellcat engine and attendant cooling weigh about 180 pounds more than the Viper V10, so you can stop right there. But if you haven't put down your shoehorn yet, know that the Hellcat V8 is way too tall to fit under the Viper's carbon-fiber hood. So just don't.

And anyway, the sensible thing to do is buy a Challenger Hellcat and enjoy the engine where it belongs. Because it only costs $60,990 for the manual model, which is insanely cheap for America's most insane engine.

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